1. Field of the Invention
The present invention relates to a pattern forming method and in particular to a pattern forming material capable of forming a pattern which has excellent resolution, and a substance adherence pattern material obtained by using said pattern forming material.
2. Description of the Related Art
An image forming method that utilizes a method of forming a hydrophilic/hydrophobic pattern has been widely used. In particular, an image forming method comprising adhering a colorant to a region has been widely used.
For example, an image forming method is employed in which a hydrophilic/hydrophobic pattern is on the surface of an image-receiving material, then an image is formed by utilizing a difference in adsorptivity of a hydrophilic or hydrophobic surface toward a visualizing material. Further, various methods of forming a hydrophilic/hydrophobic pattern are employed to form a display material, a planographic printing plate material and a semiconductor integrated circuit material.
Particularly from the viewpoint of particularly improving the resolution of a formed image, a method of forming a fine hydrophilic/hydrophobic pattern is attracting attention. As the method of forming a hydrophilic/hydrophobic pattern, there is disclosed a method in which a surface of a plate which surface has a convex pattern adsorbs a hydrophobic molecule, the hydrophobic molecule is transferred to an image-receiving material, and then a hydrophilic molecule is adsorbed by non-transferred regions on the image-receiving material, whereby a hydrophilic/hydrophobic pattern is formed on the image-receiving surface. This method is useful for production of various functional devices and DNA chips (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2002-283530). This method of forming a hydrophilic/hydrophobic pattern can be used to form a precise pattern. However, in order to obtain such a precise pattern, a special material is required and further, it is difficult to apply the method of forming a hydrophilic/hydrophobic pattern to formation of an image with a large area.
Regarding application to formation of an image with a large area, there is known a planographic printing plate material. When the planographic printing plate material is used, a hydrophilic graft polymer is formed on the entire area of a hydrophobic substrate, and the hydrophilic graft polymer is image-wise released from the surface of the substrate by exposure to laser light to form a hydrophilic/hydrophobic pattern comprising the hydrophilic graft polymer and the hydrophobic surface of the substrate, then an ink and water are allowed to adhere thereto based on the pattern (for example, JP-A No. 11-119413). According to this method, a hydrophilic/hydrophobic pattern with a large area can be formed. However, because high energy is required for releasing the hydrophilic graft polymer, an expensive high-power laser is required to form an image. Moreover, the qualities and resolution of the formed image are not satisfactory.
Another application of the hydrophilic/hydrophobic pattern is a technique for arranging fine particles in pattern.
Techniques of arranging fine particles are techniques important for achieving higher functions such as larger area, higher resolution and higher density of materials for catalysts, recording materials, sensors, electronic devices and optical devices. Such techniques are extensively studied.
For example, a method of forming aggregated fine particles is proposed in which a liquid dispersing medium containing fine particles is developed on a substrate to form a liquid thin coating thereon, the thickness of the liquid dispersing medium is decreased to a thickness equal to or thinner than the particle diameter, and the fine particles are aggregated by surface tension (see, for example, Japanese Patent No. 2828374). According to the invention described in Japanese Patent No. 2828374, a layer of fine particles can be regularly aggregated and uniformly arranged. However, it is difficult by the invention described in Japanese Patent No. 2828374 to obtain a patterned arrangement of the fine particles in a desired region.
As a technique for arranging fine particles according to a pattern, there is described a method in which the surface of an oxide substrate such as TiO2 is irradiated with patterned light to prepare a hydrophilic/hydrophobic pattern on the surface, and fine particles are arranged based on the pattern (see, for example, JP-A No. 2002-273209). According to this method, a pattern of fine particles can be formed. However, since the fine particles are merely physically adsorbed without fixation and easily released, the pattern of fine particles is unsuitable for use in various devices. Further, the fine particles tend to adhere to a region other than the particle-adhering pattern, and there is a demand for a method of forming a pattern highly selectively to prevent the particles from adhering to a region other than the pattern.
As another technique of arranging fine particles according to a pattern, a method of laminating fine particles according to a pattern by using a micro-stamp is known as shown by G. M. Whitesides et al. (E. Kim, Y. Xia, G. M. Whitesides, Advanced Materials, vol. 8, p. 245, Wiley lnterscience, 1996). According to this method, fine polymer particles of submicron size can be accumulated in order without adhering to other region than the pattern, thus a pattern can be obtained highly selectively. However, in this method, the procedure is difficult and the rate of solvent evaporation should be controlled in order to prepare an ordered laminate of particles, therefore the particle laminate cannot be easily produced. Further, since the area of the producible laminate is small, this method is unsuitable for producing a laminate with larger area. Also in this method, the adsorption strength of the fine particles laminated according to a pattern to a substrate is weak. Therefore, higher adsorption strength of the fine particles to the substrate is required from a practical point of view.
Another application of the hydrophilic/hydrophobic pattern is a technique regarding a conductive material. Conventionally, various conductive pattern materials have been used for formation of circuit boards (see, for example, Ei Kazuta, Purinto Haisennbann No Seizougijutsu (Techniques of Manufacturing Printed Circuit Boards) (CMC Publishing Co., Ltd., 2001). Typically, such conductive pattern materials are obtained by providing, on an insulating material, a thin conductive material by a known method such as vapor deposition, by treating it with a resist, by removing a part of the prepared resist by exposure to patterned light, and by etching the material to form a desired pattern. However, such methods require at least 4 steps. Moreover, when wet etching treatment is carried out, a step for disposal of waste solution is also required. Hence, the process has to be complicated. As another method of forming a pattern, a method of forming a conductive pattern material by using a photoresist is also known. This method involves applying a photoresist polymer onto a substrate or sticking a photoresist on a dry film to a substrate and then exposing the substrate via an arbitrary photomask to UV rays to form a checked pattern or the like. This method is useful for formation of an electromagnetic wave shield which requires high electrical conductivity.
As micromachines are further developed and ultra-LSI is further downsized, a finer wiring structure is also required to nano-degree. However, there is a limitation of finer processing by metal etching, and the breaking of fine wires during processing is worried about. Accordingly, a method has been desired by which a precise pattern with regulated orientation can be formed.
Meanwhile, regarding a conductive material, a method has been paid attention to in recent years in which a pattern is formed directly from digitalized data without a mask. Various proposals regarding the method have been made (see, for example, JP-A No. 2002-324966).
By utilizing such methods of forming a digitalized pattern, arbitrary formation of fine patterns can be expected. One of these methods is a method of using a self-organizing monomolecular film. This method utilizes a molecular aggregate formed spontaneously when a substrate is dipped in an organic solvent containing surfactant molecules. For example, a combination of an organosilane compound and a SiO2 or Al2O3 substrate or a combination of an alcohol or an amine and a platinum substrate can be used to form a pattern by light lithography or the like. Such a monomolecular film enables formation of a fine pattern. However, since the substrate/material combination usable in the monomolecular film is limited, it is difficult to put the method to practical use. The technique of forming a fine wire pattern which can be practically employed has not yet been established.
From the viewpoint of lightweight, flexibility and environmental compatibility, an organic transistor using a conductive polymer pattern has been studied. A support using such organic material is characterized by that the support is light, thin, and flexible and that an element with a large area can be easily (by the same printing technique as in printing at room temperature) prepared by using such support. By combining these characteristics with electrical and optical characteristics of new organic semiconductor which is being developed, new development can be expected in techniques for personalization of information which is most strongly demanded in the present information technology. Such technique is, for example, techniques of producing wearable portable terminals having simple information processing functions and easily manipulatable input/output functions.
However, any of these techniques do not satisfy demands from practical viewpoints such as durability, stability of conductivity, applicability to larger area, and manufacturing suitability.